HER2 Vaccine Shows Promise in Early-Stage Breast Cancer

Anti-HER2 DC1 vaccination was demonstrated to be a safe and immunogenic treatment to induce tumor-specific T-cell responses in patients with HER2-positive breast cancer, according to the results of a randomized selection design trial.

The pathologic complete response (pCR) rate was higher in patients with ductal carcinoma in situ (DCIS) compared with patients with invasive breast cancer (28.6% vs 8.3%). Patients with DCIS who achieved a pCR (n = 12) and who did not achieve a pCR (n = 30) had similar peripheral blood anti-HER2 immune responses.

“In this study, we compared where we injected them, and it didn’t seem to make any difference as far as either inducing an immune response or causing regression of the tumors,” said lead study author Brian J. Czerniecki, MD, PhD.

In an interview with OncLive, Czerniecki, chair, Department of Breast Oncology, Moffitt Cancer Center, discussed the significant findings of this trial and the importance of developing cancer vaccines.

OncLive: Can you begin by describing the vaccine and the trial in which it was tested?

Czerniecki: It’s a dendritic cell vaccine, which means it’s made from the patient’s own immune-stimulating white cells. Most vaccines, when they’re administered off the shelf, contain a lot of things to stimulate this particular cell to take up and activate the immune response, so we actually directly take those cells out of the patient’s blood, activate them out of their body away from the influence of cancer, and then inject them back into the body. What we feed them is little bits of this HER2 protein, so that’s why it was targeting HER2.

The patients in this study happened to be patients with early breast cancer, meaning either early stage I or DCIS. Those are the patients who were targeted in this trial, but we also have trials where we administer the same vaccine for patients who have invasive HER2 breast cancer who are at risk for recurrence. In other words, they’ve been treated with all the standard stuff, and they’re still at risk for recurrence. We’re vaccinating them to try to prevent recurrence as well.

This particular study, though, included those treated with DCIS and early-stage breast cancer. We treated them with the vaccine before the patients went on to surgery, and in about 29% of them, the tumor actually disappeared before they went to surgery—if they had DCIS. This was not the case for patients with invasive cancer. And that’s been known for years, that cancer vaccines aren’t all that effective when someone has an active tumor to try to treat it. So that wasn’t necessarily surprising. I think the earlier people have the disease, or if you treat them in a setting where there’s minimal disease—in other words, where they’ve been completely treated and they’re at risk for recurrence—that’s the setting where vaccines likely work best.

Were there any noteworthy toxicities associated with the vaccine?

The toxicities were pretty minor—mostly grade I or II. Patients experience some soreness from the needle poke, some get some fatigue or fever for a couple hours, but very limited side effects overall.

Did there appear to be any differences in the results depending on the site of injection?

No. In this study, we compared where we injected them, and it didn’t seem to make any difference as far as either inducing an immune response or causing regression of the tumors. It worked whether we gave it in the breast in the area where the DCIS was, or if we gave it in their lymph nodes.

The immune response was a little bit stronger if people got it directly into the lymph node, but it wasn’t statistically significant. You’re getting all the cells directly to where they need to interact with the immune cells in the lymph node, so it would potentially be a little stronger there.